1. Field of the Invention
This invention generally relates to solar collectors and specifically to solar collectors wherein a plate of heat absorbent material is disposed in intimate engagement with a tube grid by compression but without any bonding or soldering of the two together.
2. Prior Art
With the rising cost of fossil fuels, attention is being directed to the utilization of solar energy. Numerous heat exchange devices have been created wherein the sun's rays are applied to the elevation of temperature of various fluids. In many of these devices, a tube grid is utilized for containing fluids and liquids capable of having their temperature raised and such tube grids are disposed in contact with an absorber plate. The tube grid is maintained in intimate engagement with the absorber plate often by a bonding operation wherein solder causes the intimate adherence of the one to the other. The use of welding or adhesives has also occurred. Such practices increase the cost of the solar collector by reason of the labor and materials utilized in bonding. There are further disadvantages in bonding or soldering in that flux residues may remain on the absorber plate or be entrapped in the fluxes and cause the deterioration of the solder bond as well as the absorber plate and the tube grid. High temperature may accomplish differential expansion. As a result, the tube grid and the absorber plate may become detached from one another, destroying the intimate contact. Temperatures of over 600.degree. Farenheit are not unknown. Welding involves subjecting the parts to even higher temperatures and often results in warpage or distortion of the absorber plate, requiring a straightening of the plate and producing an unattractive appearance. If the absorber plate has applied to it, a coating to enhance the absorption of the sun's heat rays, such a coating may be impaired by bonding or soldering or welding. Sonic welding also causes the delamination of preapplied coatings. Electrodeposition is another means of applying coatings that enhance absorption of the sun's rays. Black chrome dress on an absorber plate may cause the entrapment of cleaning and plating solutions and greatly reduce long term durability. Mechanical clips are often made of different metals than the absorber plate. When such different metals are brought together by welding or soldering or other means, galvanic action may result in rapid deterioration and detachment. Such clips may be dimensionally misapplied or may become loose due to thermal expansion and contraction of the different metals, thus impairing the intimate contact of the tube grid with the absorber plate. In many of these methods, handling costs are increased. The increased cost of other methods becomes justified by reason of permanence.